Rust proofing composition and method of making the same



Patented Jan. 19, 1932 v UNITED STATES PATENT OFFICE MATTHEW GREEN AND ELMEB M. JONES, OF DETROIT, MICHIGAN, ASSIGNOBS TO PARKER BUST-PROOF COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN RUST PROOFING COMPOSITION AND METHOD OF MAKING THE SAME No Drawing.

Our invention relates to the art of rustproofing iron by coatin articles composed of, or containing, iron wit 1 a layer of insoluble phosphates of iron and manganese.

Iron forms a series of phosphates ranging from high acid salts to basic salts. The high acid salts are soluble in water, whereas the low acid and basic salts are substantially insoluble.

It is well known that iron can be rustproofed by formin on its surface a coating of insoluble low acid or basic, phosphates of. iron. This has been done extensively by immersing iron articles in a dilute heated solu-- tion of phosphoric acid containing a certain amount of phosphates of iron, of manganese, or ofboth. The coating appears to be formed only when there is a series of phosphates present, constituting what is commonly known as a balanced solution. This solution has been prepared in various ways. Our invention relates to novel materials for forming the solution,.and a process for forming the materials and method of using the materials.

Our preferred material is a powdered or granular substance containing a large proportion of high acid phosphates of iron and manganese with a sufiicient quantity of lower acid phosphates so that, when the material is mixed with the proper proportion of water, a substantially balanced solution is formed. Coating begins immediately upon immersing iron articles in such a solution. a

In forming this material, we first mix the ordinary commercial, approximately solution of phosphoric acid with iron filings or other iron fragments. While it is not necessary, it is highly desirable to heat the acid to about 100 (1. before allowing it to re-act with the iron. The mixture is stirred vigorously while the acid is slowly added, so as to constantly bring the fresh acid into direct contact with iron. When strong phos phoric acid contacts iron, hi h acid salts are formed. Weaker acid, or tie acid salts in contact with iron, form the lower acid and insoluble salts. By forming the mixture in the manner stated, a maximum of high acid salt is formed with aminimum of the low acid salt. 7 7

Application ill ed October 24, 1925. Serial No. 84,569.

The addition of acid and the stirring is continued until a stifily plastic mass results.

This normally results when about two quarts of acid have been added to one pound 2.29 ounces of iron.

W hen the stifily plastic stage of the mixture is reached, manganese dioxide is added.

lVe prefer to use about 4.96 oz. man anese dioxide to the pound of iron, but di erent proportions, or other compounds containing manganese, may be used. The addition of the manganese dioxide results in the formation of readily soluble high acid phosphates of manganese, and the mixture becomes apparently wetter, and less stiflly plastic.

As a final step, sludge or manferine, which will be described later, is stirred into the mixture until the whole becomes comparatively dry, so that it ma be granulated or powdered. An amount 0 sludge or. manferine equal to 5.84 oz. to each pound of iron is found satisfactory in a mixture such as described above. This is an amount of the dry sludge in weight equal to about onetwentieth the weight of the mixture to which the sludge is added. Considerable variation from the stated proportion of sludge is permissible.

In coating iron with a balanced solution, as described above, a sediment or deposit is formed which falls to the bottom of the treating tank. Where the process is continued for a considerable time, with the addi-- tion of fresh solution as the old solution de preci-ates in strength, a considerable quantity of this deposit or sludge accumulates. The composition of this sludge is very complex, and it is not deemed necessary to attempt an accurate statement of its chemical composition. Apparently it consists largely of slightly soluble or insoluble phosphates, such as form the rust proofingI coating, and some more highly acid salts. ereafter, Where the term sludge is used, the deposit formed in the manner described in a rust-proofing tank is meant, and manferine is a. term applied to-this sludge where manganese is included in the rust proofing solution.

The sludge or manferine, upon removal from the tank and drying, becomes a highly absorbent mass, and its use in the mixture accomplishes two purposes. In the first place, it dries out the mlxture, so that it can be readily handled as a granular or powdered product. In the next place, it adds the elements necessary to balance the solution, so that a mixture of the material with water produces a solution ready for immediate use.

There is a tendency for the mixture to harden into a solid mass. This tendency is lessened by heating the phosphoric acid before allowing it to re-act with the iron, and therefore such heating is desirable, as stated above. Even when carefully formed, the granular mass has a tendency to cake upon standing. The cak'ed product may be ground, and this ground material has comparatively little tendency to cake, and is advantageous in this respect over the freshly formed granules, where it is likely to stand for a considerable period before use.

The material roduced as described is convenient to hand e, and can be shipped more easily as well as more cheaply than phosphoric acid, which is usually shipped in caroys for use in rust-proofing.

Simple instructions enable anyone to mix the proper amount of material with water and-- produce a balanced solution ready to begin the coating operation. The proportion of the powdered or granular material to the water used may be varied considerably, but a weak solution is used. We have found the proportion of one ounce of the owder to two quarts of water fairly satis actory. This material is particularly advanta eous where a comparatively small amount of rust proofing is to be done, or where the rust proofing is done at intervals, in contrast to being a substantially continuous operation.

Where free acid is present in the coating solution, crystallized phosphates are apt to be formed as a art of the coating. These crystals are liable to admit moisture around them, so that a coating having the crystals, commonly referred to as sparkle, is less efficient than a coating free from crystals. In the material prepared as described above, the phosphoric acid is so thoroughly combined with iron and man anese that sparkle is practically eliminate The manganese dioxide may be omitted, or other compounds substituted, and sludge may be used from a tank where manganesawas not present in the solution, but we have found it easier to retain a satisfactory percentage of acid phosphates in solution where manganese is present, as the phosphates of manganese are more soluble than the corresponding phosphates of iron, and therefore we prefer to add'manganese dioxide, as described above, and to employ manferine for the added sludge.

The high acid phosphates may be prepared as described above,

either with or without the manganese dioxide, and the sludge omitted, in which case it is somewhat more diflicult to prepare a satisfactorily dry mixture, although this may be done in various tion. In starting the coating action, where a mixture without the sludge is used, the solution must be allowed to attack iron until enough sludge is formed to balance the solution before the most eflicient coating can be done; but after the coatin operation has been started, the material without slud e may be added to renew the solution, thereieing sufficient sludge present in the tank to balance the solution.

The material containing sludge may be used not only for starting the coating operation, but for renewing the solution, where this is most convenient. A good way, where convenient, is to use the balanced material to start the operation, and to renew the smution by adding the compound without sludge.

It will be readily understood that the specific description given above is given merely to enable those skilled in the art to understand how our invention may be practiced, and that, while some variations have been mentioned, no attempt has been made to describe all of the obvious variations in our invention, the scope of which is defined in the appended claims.

What we claim is:

1. The method of making a rust-proofing compound, which comprises stirring iron fragments while mixing therewith commercial phosphoric acid until the mixture becomes stifily plastic, and thereafter adding 105 an absorbent material until the mixture assumes a granular or powdery condition.

2. The method of making a rust-proofing compound, which comprises stirring iron fragments while mixing therewith commerno cial phosperic acid until the mixture becomes stifily plastic, and thereafter adding sludge to the mixture.

3.'The method of making a rust-proofing compound, which comprises stirring iron fragments while mixing therewith commercial phosporic acid until the mixture becomes stifiiy plastic, and thereafter adding manferine to the mixture.

4. The method of making a rust-proofing compound, which comprises stirring iron fragments while mixing therewith commercial phosphoric acid until the mixture becomes stifliy plastic, thereafter stirring into the mixture manganese dioxide, and thereafter adding sludge in an amount substantially equal to 5.84 oz. for eachpound of iron used. 5. The dprocess of forming a rust-proofing compoun which comprises stirring iron fragments while slowly adding thereto an aproximately solution of phosphoric acid until the amount of solution added is substantially in the proportion of two quarts to one pound 2.29 ounces of the iron used, thereafter stirring in manganese dioxide in substantially the proportion of 4.96 oz. to the pound of iron, and finally stirring in manferine to an amount substantially equal to 5.84 oz. for each pound of iron.

6. The method of making a rust-proofing compound, which comprises stirring iron fragments while mixing therewith hot commercial phosphoric acid until the mixture becomes stifily plastic, and thereafter adding an absorbent material until the mixture assumesa granular or powdery condition.

7. The method of making a rust-proofing compound, which comprises stirring iron fragments while mixing therewith hot commercial hosphoric acid until the mass becomes stlflly plastic, then stirring a manganese compound into the mass, and thereafter adding a granular absorbent material until the entire mixture assumes an apparently dry granular condition.

8. The method of making a rust-proofing compound, which comprises stirring iron fragments while mixing therewith hot commercial hosphoric acid until the mass becomes stlfily plastic, then stirrin a man anese compound into the mass, an therea r adding a granular absorbent material until the entire mixture assumes an apparently dry granular condition, allowing the ranular material to stand until it cakes, an final- 1y grinding the caked mass.

9. A rust-proofing com ound, comprising a granular or owdery su stance containing high acid ort o-phosphates of iron and enough low acid and basic phos hates of iron so that when the substance is mixed with water, a balanced solution is produced which will immediately begin coating iron immersed therein.

10. A rust-proofing compound, comprising a granular or powdery substance containing high acid phosphates of iron and manganese and low' acid and basic phosphates of iron and man anese, the low acid and basic phosphates being, in the dry state, about onetwentieth b weight of the amount of the high acid p osphates. p

11. The rocess of rustroofing iron articles, whic comprises mixmg a granular or 12. The process of rust-proofing iron articles, which comprises immersing iron articles in a solution containing high acid phosphates of ironand manganese, maintaining the solution hot, removing the articles after they become coated and adding other artaining high acid ortho-phosphates of iron.

In testimony whereof, we have hereunto signed our names to this specification.

MATTHEW GREEN. ELMER M. JONES.

powdery substance containing high acid phosphates of iron and manganese and low acid and basic hosphates of iron and manganese with sufliclent water to form a dilute solution, heating the solution, immersing iron articles in the solution, removing the articles as they become coated and adding other articles to be coated, and maintaining the strength of the solution by adding only high acid orthophosphates of ironand manganese. 

